The mechanisms by which satiety is produced in young pigs is being investigated. The emphasis is upon feedback signals originating in or associated with the gastrointestinal tract which bring a meal to an end. Isotonic and hypertonic solutions of glucose and lactose and hypertonic solutions of sodium chloride have depressed food intake in hungry pigs. Further research will be designed to determine where such solutions act and the means by which information is transmitted from possible glucoreceptors and osmoreceptors in the gut to the brain. Whether sugars need be actively absorbed from the intestine will be probed by comparing the satiety-effectiveness of sugars actively absorbed, e. g. galactose, with that of those passively (and slowly) absorbed, e. g. xylose. Site of glucose and osmotic satiety effects will be studied by infusing such solutions through catheters implanted in different parts of the gastrointestinal tract and by the use of thirty fistulae of similar sectors of the tract. Intrathoracic section of the vagi will be used to study neural transmission of feedback signals. The role of cholecystokininpancreozymin as a humoral feedback signal will also be further studied. BIBLIOGRAPHIC REFERENCES: Houpt, K.A. and Houpt, T.R. The effects of gastric loads and food deprivation on subsequent food intake in suckling rats. Jour. Comp. Physiol. Psychol. 88:764-722, 1975. Houpt, K.A. and Gold, R.M. 1975. Glucoprivic eating in rats despite knife cut induced hypothalamic hyperphagia. Pharm. Biochem. Behav. 3:538-588.